Metal straightener



y 1942- w. K. BECKWITH ETAL 2,282,111

METAL STRAIGHTENER Filed Jan. 2, 1941 H I vzw'roRs l I avl zl/ igggm/ ATTO RNEY.

Patented May 1942 METAL STBAIGHTENEB Wendell K. Beckwith, Milwaukee, and William H. Lieber, Wauwatosa, Wis asaig'nor: to Milwaukee Electric Tool Corporation, Milwaukee, Wis, a corporation of Wisconsin Application January 2, 1941, Serial No. 372,734

8 Claims.

' This invention relates in general to improvements in the art of shaping sheet metal structures, and-relates more specifically to improvements in the, construction and operation of mechanisms which are especially useful for repairing and for restoring damaged sheet metal parts of automobiles or the like, to their original shape.

An object of the invention is to provide an improved sheet metal straightening or shaping -assemblage, which is simple in construction and highly efflcient in use.

Many different types of so-called pneumatic fender hammers for restoring damaged sheet metal automobile parts such as fenders and bodies to their original shape, have heretofore been proposed and used with more or less success. it has long been customary in the art of straightening .distorted sheet metal, to first bump out the dents to their approximate original shape, and tothereafter iron out the rough spots with a portable pneumatic hammer preparatory to the application of the final finish. Each of these portable tools is ordinarily provided with a U- shaped manipulating frame adapted to reach on opposite sides of the damaged area, and having.

a work-engaging reaction dolly or anvil die secured to one end, and a pneumatic hammer adjustably suspended from its opposite end and coacting with a work-engaging impact dolly or hammer die cooperable through the work with the anvil die. In order to prevent nicking of the metal and to insure smooth ironing, it is desirable to maintain the impact and reaction faces of the hammer and anvil dies approximately parvide hammer and reaction dies which are bothtiltable relative to the hammer cylinder axis so as to permit the latter together with the manipulating frame to be universally tilted, without destroying the parallel relation of the working faces of the dies. In this Johann assemblage the anvil die is universally movably supported and the active portion of the impact die is provided with an integral disk having an annular work engaging lip cooperable with the work around and remote from the die axis, for causing the two dies to tilt in unison. While the work-engaging surfaces of the Johann dies are maintained in proper relation-to the work, the assembla e is such that manual adjustment of the hammer cylinder toward the work causes both the hammer die and the guide to be continuously maintained in clamping engagement with the work surfaces, and this action is objectionable as it limits the range and action of the guiding disk which causes the-lower and upper dies to tilt in unison We have discovered, that best ironing results are obtainable and'manipulation of such a tool is facilitated, not only by permitting the dies to tilt freely relative to the cylinder and frame, or vice versa, but by also forming the guide separate from the impact die and permitting the dies to float or refrain from directly clamping the work therebetween when no blows are being delivered.

It is therefore a more specific object of the present invention to provide a new and useful portable fender hammer assemblage embodying the desirable features of the prior art structures hereinabove referred to, while avoiding the un-' desirable features thereof; and which can be readily manipulated to perform perfectly.

Another specific object of the invention is to provide a pneumatic sheet-metal straightener having cooperating anvil and hammer dollies which are tiltable in unison with respect to their supporting and actuating structures, but which v do not clampingly engage the intervening work smoothed, and since such tilting is necessary when working in cramped quarters and upon surfaces curving in all directions, this prior tool was insufliciently flexible for most effective general use.

except at the moment of impact, by virtue of the fact that the hammer die is freely axially movable at all other times. I

A further specific object of our invention is to .provide an improved sheet-metal hammering assemblag'e wherein a tiltable anvil die cooperates with a full floating or freely movable hammer die provided with a resiliently mounted guiding element for causing the two dies to tilt in unison so hammer having a U-shaped work spanning frame, an'anvil or reaction die carried by one end of the frame, and a pneumatic hammer adjustably associated with the opposite end of the frame, wherein the frame and cylinder assembly may be universally tilted relative to the work, and in which the work is not continuously clamped between the two dies because the impact die is not positively held against the work surface.

, An additional specifiic object of this invention is to provide a metal ironing assemblage which can be manipulated and moved along the work with greatest of ease, and dexterity, which is durable and compact in structure, and which may be manufactured and operated at moderate cost.

These and other specific objects and advantages of the invention will be apparent from the following description; and the present invention constitutes an improvement on the disclosure in said Johann application so that patentable features shown and described but not claimed herein, constitute part of the Johann invention.

A-clear conception of the improved features constituting our present invention, and of the mode of constructing and of utilizing a sheet metal ironer built in accordance therewith, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is an enlarged central longitudinal section through a fragment of a pneumatic fender hammer, showing the anvil die and the hammer die coacting with an intervening piece of sheet metal;

Fig. 2 is a transverse section through the assemblage of Fig. 1 taken along the line 2-2;

Fig. 3 is a side elevation of one of the improved fender hammers, showing the dies inactive; and

Fig. 4 is an elevation of the die and guide assemblage, showing the same cooperating with an intervening piece of sheet metal at an oblique angle.

While we have shown and described only one commercial embodiment of our improved portable sheet metal shaper, it is not the intent to thereby unnecessarily restrict the scope or utility of the invention, and it is to be understood that the improved anvil and hammer supporting frame may be of various shapes, depending upon the specific service for which the tool is to be used.

Referring to the drawing, the improved portable pneumatic fender hammer shown therein, comprises in general, a tubular U-shaped frame 6 having one approximately vertical end 'I and another approximately horizontal end 8; a reaction dolly or anvil die 9 universally movably supported upon the vertical frame end I by means of a semi-spherical element I0; an impact dolly or hammer die II cooperating with the anvil die 9 and being universally movably suspended from the lower cylinder head or bushing I2 by means of a guide sleeve I3 and other structure cooperating therewith; a pneumatic hammer assemblage consisting of a cylinder I4 closed at one end by the bushing I2 and an impact plunger or piston I5 reciprocable within the cylinder and cooperating with an impact pin I5 slidably confined within the bushing I2; a T-fitting I6 detachably secured to the horizontal frame end 8 by means of a clamping bolt I1, and having a bore I8 within which the hammer cylinder I4 is upon which the anvil die 9 is freely tiltably suspended, is preferably permanently attached to the tube end I while the die 9 may be removed from the top or spherical seating of the element 9. The anvil block or lower die 9 is of rectangular shape and is provided with an upper smoothly curved work-engaging surface 22 rounded at its edges, and several of these dies 9 having different shapes, curvature, and sizes of surface 22, may be provided for performing different classes of work. The anvil die 9 besides being freely universally tiltable in all directions relative to the frame 6,.and vice versa, may also be freely rotated relative to the frame end I, thereby permitting the frame 6 to be tilted or swung about the anvil axis without displacing the anvil die 9. v

The impact dolly or hammer die II which is freely axially slidable within the guide sleeve I3, is also embraced by a disk-like guide element 23 having an annular lip 24 and an integral c01- lar 25 snugly embracing the sleeve I3. The impact die II is adapted to coact with the sheet metal 2| in opposition to the anvil die 9 as shown in Figs. 1 and 4, and this die II is circular in shape and is freely slidable along and rotatable about its axis within both the sleeve I3 and the element 23 but is prevented. from dropping out of place by an annular flange 26. The annular lip 24 of the guide element 23 is adapted to engage the upper surface of the sheet metal 2| so as to simultaneously tilt the two dies 9, II relative to the longitudinal axis of the bushing I2 and cylinder I4; and in order to permit such tilting the sleeve I3 and the upper end of the hammer die II are provided respectively with spherical zone surfaces 21, 28 coacting with the adjacent ends of the bushing I2 and impact pin I5. The guide sleeve I3, disk element 23, and hammer die II are resiliently and removably suspended from the lower end of the cylinder I4, by means of a coil spring 29 the lower end of which engages a socket 30 in the element 23 and the upper portion of which frictionally embraces the cylinderhead bushing I2 and abuts against the lower extremity of the cylinder I4.

This assemblage is such that the element 23 and sleeve I3 can be moved axially toward the anvil die 9 with the cylinder I4 and head bushing i2 to flexibly but firmly clamp the sheet metal 2|, but without interfering with the free axial movement of the hammer die II or causing this die to clampingly engage the sheet metal 2|; and the flexibility of the attaching spring 29 permits free tilting of the cylinder I4 and bushing I2 relative to the guide element 23, sleeve I3 and hammer'die II in any direction and at any time. The end of the bushing I2 is tapered to facilitate removal and application of the spring 29 which merely serves as an attaching means, and the interior of this bushing is counter-bored to afford clearance for the upper end of the hammer die II, while the impact pin I5 is freely slidable within the bushing I2 which is screw threaded into the lower end of the cylinder I4.

and away from the fixedly located anvil die 3,.

by means of the pinion l9 coacting with the rack teeth 20 formed on one side of the cylinder, in order to resiliently clamp the work while permitting relatively free advancement of the tool along the sheet metal 2|. The cylinder M has a main bore 32 within which the piston I is reciprocable, and also has an auxiliary bore 33 of smaller diameter within which an auxiliary piston 34 carried by the main piston I5 is slidable. The upperend of the hammer cylinder I4 is provided with an inlet port 35 communicating with a flexible valve controlled compressed fluid supply pipe 36, and with the small bore'33; and the lower portion of the cylinder I4 is provided with lower and upper spent fluid exhaust ports 31, 31'

located below and above the impact piston I5. The medial portion of the auxiliary piston 34 has an annular groove 38 therein adapted to communicate with the fluid supply port 35, and this groove 38 is connected to the exhaust space beneath the main piston l5 by a transverse opening 39 and a longitudinal passage 40 formed in by merely utilizing the button 53 to release the pinion l9 from the clutch member 48, and by subsequently sliding the cylinder |4 along the bore l8 of the fitting l5. When the anvil and hammer dies 9, II have been properly positioned below and above a piece of sheetmetal 2| which is to be straightened, the anvil die'9 may be brought into engagement with the lower surface of the work by manipulating the handle 48 to lower the cylinder l4, and to thereby bring the guide element 23 into resilient clamping engagement with the upper surface of the sheet metal this piston; but the upper end portion of the bore 33 is sealed to provide a cushion chamber 4|.

As heretofore indicated, the pneumatic hammer assembly is slidable within the bore |8 of t the fitting "5, by means of the pinion l9 coacting with the cylinder teeth 20, and the pinion I9 is secured to a, shaft 42 by means of a key 43, this shaft 42 being rotatably mounted in a removable plug 44 adapted to be removably secured to the T-fltting I6, see Figs. 1 and 2. The pinion shaft 42 has a central bore 45 at one end, and is provided with an actuating crank handle 48 at its opposite end; and the end of the pinion l9 which faces the plug 44 is provided with an annular series of radial ratchet teeth 41 adapted to coact' with similar teeth formed on one side of a clutch member 48 slidably mounted upon the shaft 42 between the pinion I9 and plug 44. While the member 48 is movable along theshaft 42, it is locked against rotation by splines 49 ,formed integral with the member 48 and coacting with guide'slots 50 formed in the plug 44;

and member 48 is constantly urged along the shaft 42 toward the pinion l9 by means of 8.

2|. This resilient clamping of the sheet'metal 2| by the lower die 9 and the guiding plate 23, merely brings the cooperating faces of the dies 9, into approximately parallel relationship to each other, but does not cause the sheetmetal 2| to be clamped between these two dies. The

manipulation of the handle 46 may be carried on to such an extent that the flexible clamping of the sheet metal 2| between'the lower die 8 and the guide element 23, is not excessive, and so that the movement of the tool along the surfaces of the sheet metal 2| will not be undesirably resisted. When this preliminary adjustment has been properly effected, the frame. 5 may not only be moved along the work, but it may also be universally tilted in any direction and may also be swung freely about the common axis of the cylinder 4 and lower die support Ill. Such tilting, will not however destroy the parallel relationship between the lower die 9 and the upper die I since the guide plate 23 will function to maintain the adjacent die surfaces parallel to each other at all times.

When the tool is in approximately vertical position, th impact piston |5 will descend and rest upon the head 3| of the impact pin l5,

thereby closing ofl the'lower end olfthe passage 40 and causing the annularrecess 38 to register with the delivery end of the supply port 35.

compression spring 5| coacting with the side thereof remote from the ratchet teeth 41. While the ratchet teeth of the pinion l3 and clutch .member 48 are normally held in engagement by the spring 5|, the member 48. is adapted to be urged manually away from the pinion l9 to disengage these teeth 41, by means of a rod 52 slidable in the bore 45 and having a push button 53 at one end and a transversepin 54'at its opposite end cooperable with recesses 55 in the member 48. A

During normal use of the improved fender hammer or sheet metal straightener, the cylin-. der H of the hammer, together with the associated parts including the hammer die may be readily withdrawn away from the anvil block or reaction die 9 sufllciently to permit the parts to-be properly positioned relative to the work,

With the piston |5 in this position, the admission of compressed fluid through the port 35 will cause the fluid to flow-through the recess 38, transverse hole 39 and passage 40, to thereby quickly elevate the piston I5, sufficiently to cut on the supply of fluid to the recess 38 and to admit fluid' under. pressure to the displacement chamber above the piston l5. This admission of fluid to the upper displacement chamber is sufflciently rapid to force the piston 5v downwardly with considerable force, and as the piston l5 strikes the pin H, a blow is delivered to the hammer die The travel of the'piston I5 is thus arrested, and in moving downwardly the supply of fluid under pressure to the upper displacement chamber is cut oil, and the fluid'in this chamber will escape through the upper exhaust port 31. The piston |5 will be subsequently elevated preparatory to the delivery of another hammer blow, by the admission of fluid under pressure to the recess 38, hole 39 and passage 40,

and whenever the piston l5 iselevat'ed, the fluid under pressure thus admitted escapes through the lower discharge port 31. In this manner,

the impact piston |5 will berapidly reciprocated whenever fluid under pressure; is admitted through the port 35, and the chamber 3| above the piston 34 serves to cushion the upward movement of the piston l5 and to augment the in- ;insity of the blow"delivered thereby to the pin During this operation of the pneumatic hammer, the tool may be manipulated to cause the- (1185 9, II to travel along the roughened area of regularities therefrom. While the anvil die 9 is constantly maintained in contact with the lower surface of the sheet metal 2|, by the guide plate or element 23, the upper die II is free to float or move axially whenever no blow is being delivered thereto, and the only time that this hammer die I l isforced into contact with the up r surface of the sheet metal is at'the moment of impact. The dies 9, II are however freely tiltable so as to cause the same to properly engage the work and to remain in position with their coacting faces approximately parallel to each other, and the impact pin I5 will properly coact with the hammer die II regardless of the position of the latter, because of the provision of the spherical zone 28 at the upper end of the die II. i

From the foregoing detailed description of the operation of the improved tool, it will be noted that this tool can be effectively utilized to iron out bumps or indentations in sheet metal H to produce either plane or smoothly curved surfaces at the distorted areas. The particular mounting of the anvil and hammer dies 9, II is extremely important, since this mounting permits tilting of the frame 6 in any direction relative to the axes of the dies, and also permits swinging of the frame about these axes. element 23 and its mounting so as to permit free floating of the die I I is also especially important, since this, guide element 23 with'its inner and outer annular concentric work engaging lips has a. relatively large range of action, and thereby effectively prevents the die surfaces from assuming non-parallel relationship. The element 23 is flexibly suspended from the bushing I2, and cooperates with this bushing through the sleeve I3 and spherical zone surface 21 in such manner that relative tilting of the element 23 and cylinder I4 is freely permitted, and while the: tilting movement of the element 23 is imparted to the hammer die II, 'the clamping action of the element 23 against the sheet metal 2i is not imparted to the hammer die and does not tend to rock this die I I. relative to the die 9. It is noteworthy that the improved tool while permitting tilting and swinging of the frame 8 relative to the surfaces of the work, without destroying the parallel relationship of the dies, does not preclude the provision of means for flexibly clamping the work, and for retaining the guide element 23 in proper contact with the intervening metal. This flexible clamping tends to constantly cause the anvil die to automatically firmly coact with the depressions or low spots in the work, without making special adjustment of the clamping pressure necessary, and without reducing the impact stroke of the hammer die. This proper and constant flexible clamping action is augmented V and improved by the double concentric contact lips on the guide element 23.

While various types of pneumatic hammers may be utilized in conjunction with the improved die assemblage, the hammer structure shown and generally described herein is extremely simple and efficient. The mounting of the pinion l9 also facilitates manipulation of the tool and rapid adjustment of the cylinder and dies, and the improved assemblage has proven highly successful in actual commercial use, especially in connection with the straightening of distorted sheet metal automobile parts and the like.

It should be understood that it is not desired The guide aseaiii to limit this invention to the exactdetails of construction or to the precise mode of operation, herein shown and described, for various modifications within the scope of the claims may occur to personsskilied in the art.

We claim: 1. In combination, a portable framefan anvildie tiltably mounted upon said frame, a fluid actuated hammer bodily adjustable toward said anvil die and having a cylinder adjustably suspended from said frame and an impact piston reciprocable in said cylinder, tiltable work clamping means. interposed between said cylinder and said anvil, and a tiltable hammer die'also interposed between said anvil'and said cylinder, said piston being operable to deliver successive impacts to said hammer die and the latter being freely axially movable relative to said cylinder and said anvil die between impacts.

2, In combination, a portable frame, an anvil die tiltably mounted upon said frame, a fluid actuated hammer having a cylinder adjustably suspended from said frame and an impact piston reciprocable in said cylinder, tiltable work clamping means interposed between said cylinder and said anvil, a tiltable hammer die also interposed between said anvil and said cylinder, said piston being operable to deliver successive impacts to said hammer die and the latter being freely axially movable relative to said cylinder and said anvil die between impacts, and means for effecting adjustment of said cylinder toward said anvil die without interfering with the free axial movement of said hammer die.

ment toward said anvil die to clamp the work,

and a hammer die freely slidable within said guide element and being tiltable therewith, said piston being operable to deliver successive impacts to said hammer die and the latter being freely axially movable relative to said cylinder and said guide element between impacts.

4. In combination, a portable frame, an anvil die tiltably mounted upon said frame, a pneumatic hammer cylinder suspended from said frame and being adjustable along the cylinder axis toward said anvil die, a work engagingguide element tiltably suspended from said cylinder and being adjustable therewith, a hammer die freely slidable within said element and being tiltable therewith, and an impact piston reciprocable within said cylinder to impart sucv freely slidable alongthe axis of said guide ele- 6. In-combination, a portable frame, an anvil die freely tiltably mounted upon said frame, a

with, means for effecting adjustment of said guide element and of said hammer cylinder toward said anvil die without interfering with the free axial sliding of said hammer die, and an impact piston movable within said cylinder to impart successive blows to said hammer die.

7. In combination, a portable frame, an anvil die freely tiltably mounted upon said frame, a pneumatic hammer cylinder axially adjustable relative to said frame and toward said anvil die, a guide element freely tiltable simultaneously with said anvil die and relative to said cylinder and being adjustable simultaneously with the latter relative to said frame, a hammer die freely slidable within and tiltable simultaneously with said guide element, and an impact piston reciprocable within said cylinder to impart successive blows to said hammer die without impacting said guide element.

8. In combination, a frame, an anvil die tiltable upon said frame, a hammer cylinder adjustable upon said frame toward said anvil die, a work-engaging guide element adjustable with said cylinder and tiltable relative thereto with said anvii die, a hammer Hie freely slidable within said guide element and being tiltable therewith relative to said cylinder, and a piston reciprocable within said cylinder to deliver blows to said hammer die without impacting said guide element.

WENDELL K. BECKWITH. WILLIAM H. LIEBER. 

